4.19-stable review patch. If anyone has any objections, please let me know.
------------------
[ Upstream commit 68e2672f8fbd1e04982b8d2798dd318bf2515dd2 ]
There is a NULL pointer dereference of devname in strspn()
The oops looks something like:
CIFS: Attempting to mount (null)
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
...
RIP: 0010:strspn+0x0/0x50
...
Call Trace:
? cifs_parse_mount_options+0x222/0x1710 [cifs]
? cifs_get_volume_info+0x2f/0x80 [cifs]
cifs_setup_volume_info+0x20/0x190 [cifs]
cifs_get_volume_info+0x50/0x80 [cifs]
cifs_smb3_do_mount+0x59/0x630 [cifs]
? ida_alloc_range+0x34b/0x3d0
cifs_do_mount+0x11/0x20 [cifs]
mount_fs+0x52/0x170
vfs_kern_mount+0x6b/0x170
do_mount+0x216/0xdc0
ksys_mount+0x83/0xd0
__x64_sys_mount+0x25/0x30
do_syscall_64+0x65/0x220
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Fix this by adding a NULL check on devname in cifs_parse_devname()
Signed-off-by: Yao Liu <yotta.liu@xxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/cifs/connect.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index a5ea742654aa..f31339db45fd 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1347,6 +1347,11 @@ cifs_parse_devname(const char *devname, struct smb_vol *vol)
const char *delims = "/\\";
size_t len;
+ if (unlikely(!devname || !*devname)) {
+ cifs_dbg(VFS, "Device name not specified.\n");
+ return -EINVAL;
+ }
+
/* make sure we have a valid UNC double delimiter prefix */
len = strspn(devname, delims);
if (len != 2)
--
2.19.1
